Method and apparatus for removing condenser tubes from surface condensers

ABSTRACT

A method of removing a tube from a holder in which it is tightly held comprises loosening the tube and pulling it a short distance with an internal grasping device, grasping the tube externally with a pulling apparatus, pulling the tube a short distance out of the holder, releasing the tube, returning the apparatus toward the holder to obtain a new purchase, and repeating the pulling and return steps until the tube has been completely removed from the holder. Pulling apparatus is disclosed for performing the latter steps. An alternative embodiment includes means for cutting off the tube end after each pulling step.

United States Patent Costello Dec. 31, 1974 METHOD AND APPARATUS FOR 2,776,003 l/l957 Koster 83/636 REMOVING CONDENSER TUBES FROM 3 1m er ms SURFACE CONDENSERS 3,685,132 8/1972 Hodge 29/427 Dennis W. Costello, 306 Kemerer Dr., McCabe Acres, Greensburg, Pa. 15601 Filed: Dec. 19, 1972 Appl. No.: 316,584

Inventor:

US. Cl 29/427, 29/252, 29/282, 83/636 Int. Cl B23p 19/02 Field 6: Search 29/427, 252, 255, 263, 29/280, 282; 83/277, 580, 636

References Cited UNITED STATES PATENTS Primary Examiner-C. W. Lanham Assistant Examiner-James R. Duzan Attorney, Agent, or Firm-Ralph H. Dougherty [5 7] ABSTRACT A method of removing a tube from a holder in which it is tightly held comprises loosening the tube and pulling it a short distance with an internal grasping device, grasping the tube externally with a pulling apparatus, pulling the tube a short distance out of the holder, releasing the tube, returning the apparatus toward the holder to obtain a new purchase, and repeating the pulling and return steps until the tube has been completely removed from the holder. Pulling apparatus is disclosed for performing the latter steps. An alternative embodiment includes means for cutting off the tube end after each pulling step.

8 Claims, 10 Drawing Figures PATENIED 3 857. 158

SHEET 1 OF 4 00000000 0000000 000000 00000 g OOO O PATENTEU DEC3 1 I974 SHEET 2 OF 4 PATENTEI] DEBS 1 I974 SHEET 3 UF 4 'IHHH PATENTED UEC3 1 I974 SHEET 0F 4 CONDENSER TUBES FROM SURFACE CONDENSERS BACKGROUND OF THE INVENTION This invention relates to improvements in removing tightly held tubes from their holders, and more particularly to the removal of condenser tubes from surface condensers.

Surface condensers are used in modern power plants to provide pure condensed steam for boiler use. Surface condensers may be horizontal or vertical, and arranged for single or multiple passes of circulating water. Generally, however, a surface condenser can be described as a box of tubes Anywhere from 3,000 to 12,000 tubes are mounted in a pair of tube plates which have a number of internal support plates positioned therebetween, normally at about three foot intervals. These condenser tubes must be replaced about every 8 to years depending on the quality of the cooling water circulated through the tubes. Currently in industry, brass or copper tubes are being removed and replaced with stainless steel tubes.

Tubes are installed by simply sliding the tubes into the condenser. The tubes have a slightly smaller external diameter than the diameter of the holes in the tube plates and support plates that receive them. The tubes are then expanded by internal rolling with tube expanders to obtain a tight fit.

Heretofore, the removal of surface condenser tubes has been accomplished in one of two ways. In the first method, the tubes are cut, usually by chisel, on each side of each tube plate and each internal support plate. The butts remaining in each plate are then punched out with a round-nosed tool. In a 6,000 tube condenser, having six support plates and two tube plates, 48,000 tube butts must be removed, which requires approximately 1,536 man-hours to complete the job.

The second method consists of pulling a tube about 3 inches by use of a hydraulic tube puller, which contacts the internal surface of the tube, then pulling the loosened tubes out by hand. Hydraulic tube pullers or looseners, which are in common use today have a gripper which is inserted in a tube, then spread against the inner wall of the tube to grasp it internally, then pulled outwardly to pull the tube from the plates, usually moving the tube about 3 inches. This mechanism cannot be used to remove the tube completely as the portion of the tube external to the condenser cannot pass by the gripper support. The loosened tubes are removed by a crew of men, usually four, working on a long scaffold.

The major difficulty in this method is that the combined strength of the crew is usually insufficient to remove a tube because the tubes acquire a sag between each of the internal support plates. A block and tackle or a pneumatic tugger is used to remove these stubborn tubes.

OBJECTS OF THE INVENTION It is the primary object of this invention to provide a means of removing elongated tubes from a holder in which they are tightly held.

It is also an object to provide a means of removing condenser tubes from a surface condenser incrementally.

It is another object to provide means for severing a segment of a tube after each incremental movement of the tube.

It is also an object to provide a tube pulling apparatus which is relatively small and light, and operable by a single individual.

It is another object to provide a tube pulling apparatus that will develop sufficient power to remove stubborn tubes.

It is still another object to provide a tube pulling apparatus that can be operated quickly and efficiently by personnel with a minimum of training.

BRIEF SUMMARY OF THE INVENTION The aforesaid objects of the invention, and other objects which will become apparent as the description proceeds, are achieved by providing an improved tube pulling device for grasping a tube and pulling it from a surface condenser. The apparatus is pneumatically operated and the sequencing of the various steps is controlled by a number of microswitches. The invented apparatus requires that the tubes be pulled approximately the 3 inch distance, as does the second method outlined above. At this point, however, the tube removal apparatus grasps one end of the tube, pulls it a predetermined distance, holds it while the end of the tube is cut off, releases the tube, returns to the proximity of the end tube plate, grasping the tube once more and pulling it once again the same predetermined distance. This procedure is repeated until the tube is removed from the condenser.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS This invention is better understood by referring to the following detailed specification and the appended drawings in which:

FIG. 1 is an end elevational view of a surface condenser with its end cover partially broken away from one side, and the invented apparatus in place to remove tubes from the condenser;

FIG. 2 is a partially cut away side view of the surface condenser of FIG. 1, showing the invented apparatus in place to remove the tubes from the condenser;

FIG. 3 is a right side elevational view of one embodiment of the invented apparatus;

FIG. 4 is a top plan view of the embodiment of FIG.

FIG. 5 is a left side elevational view of the invented apparatus of FIG. 3;

FIG. 6 is an enlarged detailed elevational view with parts in section of the forward end of the invented apparatus, showing the gripping means of FIG. 3;

FIG. 7 is a sectional view of the apparatus taken along line VII-VII of FIG. 6 and showing the gripping chuck;

FIG. 8 is an end view taken on line VIII-VIII of FIG. 6 showing the front clamp;

FIG. 9 is a front view of the invented apparatus; and

FIG. 10 is a rear end view of the invented apparatus showing the cutter.

Considering now the invention in some detail, and referring to the illustrated form thereof in the drawings, the tube pulling apparatus 10 as shown in FIGS. I and 2 is mounted external to a surface condenser 12. The surface condenser includes end plate 14 and a number of internal support plates 16, which support tubes 18. The surface condenser 12 is covered by a shell 19. The tube pulling apparatus (FIGS. 3, 4, 5) has a base member or plate 20. Nose support rods 22 extend laterally from the base plate to front plate 23. Four such support rods are shown in this embodiment. Piston 25 (FIG. 6) is positioned in a central hole in front plate 23. Flange 26 of the hollow piston 25 forms with front plate 23 an annular pneumatic chamber 28, and O-ring seal 29 and piston ring 30 make chamber 28 airtight. The chamber 28 communicates with a source of compressed air through orifice 32 in the front plate and fitting 33 for air tubing 34. Tube clamp support member 35, mounted by flange 36, houses push rods 37 and pivotal clamping fingers 39. The push rods are adapted for longitudinal movement through the support member. The pivotal clamping fingers 39 are pivotally attached to support member by pivot pins 40. Each clamping finger has a tube contacting point 42, and a return spring seat 43. A pair of piston return springs are housed in recesses 46 in support member 35. The support member 35 is attached at its extremity to a tube selector ring 47. The entire tube clamp apparatus, from flange 36 to tube selector ring 47 is freely rotatable with respect to front plate 23. Ring 47 is held in position against plate 23 by a split clamping collar 48 and its associated screws 50.

A pair of pulling cylinders 53a and 53b are fastened to base plate 20 with their respective cylinder rods 54a and 54b extending through holes in the base plate 20. A crosshead 56 is fastened to the ends of the cylinder rods 54a and 5412. This crosshead, which is best shown in FIG. 6, carries an integral hollow piston 57, and an interchangeable gripping chuck 58. The central hole in the crosshead has a smooth bore 59 at one end to provide a proper seat for the piston 57 and has threads 60 at the other end to receive the gripping chuck. In this embodiment, a collar 61 is bolted onto one side of the crosshead to provide lateral support for the piston 57. Pneumatic chamber 62 is formed by collar 61, crosshead 56 and the flange of piston 57. The piston is provided with a piston ring 63 to obtain a tight fit in the cylinder wall. Threadedly removable gripping chuck 58 consists essentially of an outer tube 65, and an inner tube 66. Tube 65 is counterbored at one end to receive a return spring 68, and has an inward taper 69 at its other end. Tube 66 has a flange 71 at one end and a chuck 72 at the other end. The inner surface of the end of the chuck contains ridges 73 for firm gripping. The threaded end of the outer tube 65 has a collar 74 which jambs against the face of crosshead 56 when the chuck is inserted in the crosshead, to prevent it from being inserted too deeply. Pneumatic chamber 61 cooperates with a source of compressed air through a fitting 76 and a telescoping air supply tube 77 (FIG. 5). Tube 77 is slidably inserted in tube 78 which is connected to the source of air by a fitting, not shown.

A trigger 80 (FIG. 4) is mounted in a handgrip 81 on one of the nose support rods 22, and is connected to pulling cylinder throttle valve 82. Trigger rod 83 carries a trigger return spring 84, which is seated against spring bearing collar 86 fixed on the rod.

Tube guide 90 (FIG. 5), which is attached to base plate 20, has a flared mouth 91 in the nose side of the base plate. The guide 90 extends between pulling cylinders 53a and 53b to a tube cutoff device best seen in FIG. 10.

The tube cutter (FIGS. 5, 10) is mounted on back plate 95 which connects the rear end of the pulling cylinders 53a and 53b. Cutting cylinder 96 has a piston rod 97 connected to a knife holder 99. Cutter guide 100 is fixed to back plate 95, which plate 95 has a hole 101 to accommodate the tube being pulled from the condenser. Knife holder 99 is slidable in guide 100, but there is only a minimum of clearance between the holder and either the guide or back plate 95. Knife blade 103 has a sharp point and smooth sides in order to effect a piercing and shearing action on the tube simultaneously. A microswitch contact bar 105 is fixed to holder 99.

A hanger 108 is provided atop apparatus 10 so it may be suspended from an overhead support such as a jib crane 109 (FIG. 1) or from the uppermost portion of the surface condenser.

The operation of the invented apparatus is controlled by a number of microswitches. Microswitch 110 (FIG. 3) fixed near base plate 20, on the crosshead side of the plate, controls the air to the cutting cylinder 96 to cause piston rod 97 to retreat. (FIG. 10) Microswitch 112 controls the air to the rear of the pulling cylinders 53a and 53b to cause piston rods 54a and 54b to extend. Microswitch 114, located near the front plate 23, controls the air both to the cutting cylinder 96 to cause piston rod 97 to extend and to cause chuck 58 to grip the tube. Microswitch 116 controls the air to the front of cylinders 53a and 53b to cause crosshead 56 to move to the rear.

In operation the apparatus 10 is placed with tube selector ring 47 around a tube and against'end plate 14. The sequencing is as follows. When trigger 80 is depressed or pressed rearward, it opens throttle valve 82, feeding air to the retracting side of pulling cylinders 53a and 53b. The crosshead 56 moves rearward until it contacts microswitch 110. This halts movement of the crosshead by stopping the flow of air to the pulling cylinder and simultaneously feeds air to cylinder 96 to cause piston rod 97 to retract into cutting cylinder 96, which causes knife blade 103 to move across the hole 101, cutting any tube that may be extending therethrough. The microswitch contact bar 105 then contacts microswitch 116, causing air to be fed to chamber 28 through air line 34 to cause fingers 39 to grip the tube. Simultaneously, air is fed to the rear of cylinders 53a and 53b, causing the crosshead 56 to advance until the crosshead strikes microswitch 114. Tripping microswitch 114 causes the cutting cylinder 96 to extend its piston rod 97, moving the knife blade 103 clear of the hole while simultaneously feeding air to the telescoping air supply tube 77, which causes the gripper chuck to grasp the tube to be removed from the condenser. As contact bar 105 strikes microswitch 112, the crosshead begins its rearward movement again. The air to the tube clamping fingers in the nose section comes on as the cutting cylinder ends the cutting stroke, and the pressure is released as the cylinders 53a and 53b complete their extension stroke.

Although the embodiment shown and described includes a cutting apparatus, it is readily apparent that the cutting apparatus is unnecessary to the operation of tube removal from the condenser. The tube selector is revolvable to allow the tube clamp support rods to fit between adjacent tubes extending from the condenser. The clamping fingers prevent the tube from being pushed back into the condenser when the crosshead is moving toward the condenser to obtain a new grip on the tube.

SUMMARY OF THE ACHIEVEMENTS OF THE OBJECTS OF THE INVENTION It will be reocgnized by those skilled in the art that the objects of this invention have been achieved by providing an imporved tube pulling device having a tube gripper 58, pulling cylinders 53 and gripper return means. The device can pull a condenser tube from a surface condenser in which it is tightly held. Such tube is pulled incrementally in short movements. The tube can be severed by knife blade 103 after each incremental movement. The apparatus is small, light, easy to handle, and operable by a single individual having a minimum of training.

What is claimed is:

1. A method of removing a tube from a surface condenser comprising:

a. loosening said tube;

b. pulling said tube out of the surface condenser a sufficient distance to allow an external grasping apparatus to obtain a purchase on the tube;

c. grasping the external surface at the end of said tube with a pulling apparatus;

d. pulling said tube out of the condenser a predetermined distance;

e. releasing said tube;

f. moving the grasping apparatus relative to the tube to obtain a new purchase on the tube; and

g. repeating steps c through f until the tube has been pulled completely free of the condenser.

2. A method according to claim 1 further comprising cutting said tube after each pulling step.

3. Apparatus for removing a tube from a surface condenser comprising:

a. a base;

b. a face member connected to said base for bearing against the face of a surface from which said tube is to be removed;

c. a support member connecting said base to said face member;

d. means connected to said base for releasably grasping said tube;

e. said base having a hole therein in line with said face member and said means for releasably grasping said tube for passage of said tube therethrough;

f. piston means connected to said base for reciprocally moving said grasping means; and

g. means for releasing said grasping means from said tube.

4. Apparatus according to claim 3 in which said means for releasably grasping said tube comprises a piston actuatable chuck removably connected to said means for reciprocally moving said grasping means.

5. Apparatus according to claim 3 further comprising means connected to said base for cutting said tube.

6. Apparatus according to claim 5 further comprising tubular guide means for guiding said tube into said means for cutting said tube.

7. Apparatus according to claim 3 further comprising tubular guide means for guiding said tube through said base.

8. Apparatus according to claim 3 further comprising means for preventing movement of said tube in the opposite direction to the desired direction of tube move- 

1. A method of removing a tube from a surface condenser comprising: a. loosening said tube; b. pulling said tube out of the surface condenser a sufficient distance to allow an external grasping apparatus to obtain a purchase on the tube; c. grasping the external surface at the end of said tube with a pulling apparatus; d. pulling said tube out of the condenser a predetermined distance; e. releasing said tube; f. moving the grasping apparatus relative to the tube to obtain a new purchase on the tube; and g. repeating steps c through f until the tube has been pulled completely free of the condenser.
 2. A method according to claiM 1 further comprising cutting said tube after each pulling step.
 3. Apparatus for removing a tube from a surface condenser comprising: a. a base; b. a face member connected to said base for bearing against the face of a surface from which said tube is to be removed; c. a support member connecting said base to said face member; d. means connected to said base for releasably grasping said tube; e. said base having a hole therein in line with said face member and said means for releasably grasping said tube for passage of said tube therethrough; f. piston means connected to said base for reciprocally moving said grasping means; and g. means for releasing said grasping means from said tube.
 4. Apparatus according to claim 3 in which said means for releasably grasping said tube comprises a piston actuatable chuck removably connected to said means for reciprocally moving said grasping means.
 5. Apparatus according to claim 3 further comprising means connected to said base for cutting said tube.
 6. Apparatus according to claim 5 further comprising tubular guide means for guiding said tube into said means for cutting said tube.
 7. Apparatus according to claim 3 further comprising tubular guide means for guiding said tube through said base.
 8. Apparatus according to claim 3 further comprising means for preventing movement of said tube in the opposite direction to the desired direction of tube movement. 